<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        /*.border {
            width: 0;
            height: 0;
            border-style:solid;
            border-width: 0 50px 50px;
            border-color: transparent transparent #d9534f;
            position: relative;
        }
        .border:after{
            content: '';
            border-style:solid;
            border-width: 0 40px 40px;
            border-color: transparent transparent #96ceb4;
            position: absolute;
            top: 6px;
            left: -40px;
        }*/
        .border {
            /* 内部大小 */
            width: 0;
            height: 0;
            /* 边框大小 只设置两条边*/
            border-top: #4285f4 solid;
            border-right: transparent solid;
            border-width: 85px;
            /* 其他设置 */
            margin: 50px;
        }
    </style>
</head>
<body>
<div class="border"></div>
</body>
</html>